Microwave ovens.

[Phil Pascoe]

Ever wondered what the piece of silvery cardboard inside the microwave is? Me neither, till it fell apart. It's a wave guide or mica board, and is needed for the operation of the oven. You can buy them specifically for your oven and pay a premium or you can buy the stuff and cut it to fit (plenty available) -
https://www.amazon.co.uk/dp/B06VSG3SYS?psc=1&ref=ppx_yo2ov_dt_b_product_details

 

[ps.harris80]

Most fail when fat drips down the back of them, then every time you use the oven it gets cooked until its cooked enough to burn, then it conducts and you get a nice light show just before it burns a hole through the cover.

Some can be moulded plastic some are a composite sheet and some are mica, the last two are interchangeable if you can only get one type and yours has the other fitted.

It used to be a nice little earner in my white goods repair days.

 

[Phil Pascoe]

I had the light show.

 

[Spectric]

I will add that a microwave oven can leak microwave radiation and after a certain age should be tested for leaks with an appropriate tester. I doubt many people do and I think they get replaced before reaching an age where it could be an issue, door seals being an obvious leakage path.

 

[RogerS]

I had the light show.

So do I when I put stuff in to grill, in our combi microwave, spread on aluminium foil and then forget and hit Microwave.

 

[trvlr]

Where do you place/situate the aluminium foil?

 

[Ozi]

Many year ago my Dad got a free microwave leak detector from Readers Digest. Ran this plastic block containing a few electrical bits and pieces around the oven door, it was supposed to light if there was a leek. No light, does this thing really work thinks Dad and puts it in the oven to check. Bits of flying plastic also break wave guides.

 

[ps.harris80]

I used to have a high end meter and tested thousands in my day job at the time and only ever encountered 2 that leaked, one had a crack
In the door choke, what is often referred to as the seal and one that had managed to burn a hole in the back of the cavity.

There were loads of cheap MW meters that used to go into the red if pointed at a fluorescent tube so we're useless at detecting leaks around a MW.

Even if it did leak it was not really dangerous as if it failed at for example at the door, it would pass if the detector was held 25mm away from the door, once in the open air the waves dissipated very quickly so only likely to do harm if you put your hand were the leak was.